21362640 has 160 divisors (see below), whose sum is σ = 73495296. Its totient is φ = 5099520.

The previous prime is 21362633. The next prime is 21362641. The reversal of 21362640 is 4626312.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21362640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21362641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 127837 + ... + 128003.

Almost surely, 2^21362640 is an apocalyptic number.

21362640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21362640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36747648).

21362640 is an abundant number, since it is smaller than the sum of its proper divisors (52132656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21362640 is a wasteful number, since it uses less digits than its factorization.

21362640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 237 (or 231 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 21362640 is about 4621.9736044248. The cubic root of 21362640 is about 277.4714523023.

Adding to 21362640 its reverse (4626312), we get a palindrome (25988952).

The spelling of 21362640 in words is "twenty-one million, three hundred sixty-two thousand, six hundred forty".